The present invention is generally related to tire pressure monitoring systems, and, more particularly, to a receiver for receiving information from an external source relative to a tire pressure monitoring system.
Tire pressure monitoring systems (TPMS), such as may be prescribed by governmental regulations, are becoming prevalent in automotive applications. See, for example, 49 CFR Part 571, Titled “Federal Motor Vehicle Safety Standards: Tire Pressure Monitoring Systems; Controls and Displays”, regarding governmental regulations in the U.S. One basic configuration of a TPMS generally includes various components, such as a pressure sensor, a transmitter and a microprocessor that may be assembled within the interior of the tire. Most TPMSs are self-powered by a battery.
To reduce system costs and power consumption, the TPMS may not include a receiver. However, communications from an external source into the TPMS may be problematic since the TPMS transmitter is not generally designed to receive signals, but is designed just to transmit them. Communications from an external source or device may be useful for supplying various types of information to the TPMS, such as training the system to know wheel sensor location in the vehicle, e.g., Front right, Front left, Rear right, Rear left, spare tire location, or performing calibration of the pressure sensing device, if optionally desired, etc. However, the addition of receiving capabilities to the TPMS requires additional circuit complexity and increased power requirements.
While receiver circuits have been proposed for use in TPMS applications, the proposed circuits have relatively high power requirements compared to TPMS applications not using a receiver. In addition, proposed TPMS receiver circuits require running the microprocessor at a relatively fast clock rate, such as corresponding to the frequency of the externally derived signal, and, consequently, exhibit a relatively high power consumption rate. It will be appreciated that because of the location of the TPMS, i.e., within a tire, it is desired to minimize power consumption so that users are not burdened with frequent TPMS maintenance, such as battery replacement.
In view of the foregoing issues, it would be desirable to provide a reliable, low power, and low-cost TPMS receiver that allows communicating information, for example, to the microprocessor of the TPMS, for performing various operational functions, such as testing, calibration (if optionally desired), TPMS training, etc.